The second contained 52,000 cubic meters of fuel oil. It was not immediately clear how full the third tank -- also with a capacity of 52,000 cubic meters -- was.
Firefighters had been battling to prevent the third tank from catching fire, dousing it with water to keep it cool, but ultimately to no avail.
The depot, built in the 1980s and modernized several times, supplies the Antonio Guiteras thermoelectric plant, the largest in the communist nation.